LaGuardia International Airport is shown in this file photo. AP Photo/Frank Franklin

NEW YORK — Full-body scanners that use X-rays to peer through airline passengers’ clothing are being removed from John F. Kennedy and LaGuardia airports, the Transportation Security Administration said Sunday.

The ongoing removal of two dozen so-called X-ray backscatter scanners from JFK, following the removal of a small number of the machines at LaGuardia, means all three of the region’s major airports will be free of body scanners that essentially work like standard chest X-rays, and have raised health concerns because they emit radiation. Newark Liberty International Airport has always been equipped with so-called millimeter wave scanners, which do not use X-rays.

The TSA steadfastly maintains that X-ray scanners are safe, and Sunday the agency said health concerns were not why they were being removed from JFK, LGA and other major airports around the country. Rather, TSA spokeswoman Lisa Farbstein said X-ray scanners were being replaced by so-called millimeter wave scanners, which work faster than the X-ray variety and therefore help speed passengers through security checkpoints.

Kennedy, LaGuardia and Newark consistently rank near the bottom in terms of airport delays.

"In an effort to ensure the most efficient and effective use of security technology, TSA is strategically reallocating backscatter advance imaging technology units," Farbstein said in a statement.

The removal of X-ray scanners at some airports was first reported by ProPublica, the investigative news organization.

Millimeter wave scanners are not just faster than the X-ray type. Their use of radio waves to peer through passengers’ clothes, rather than radiation, has not raised cancer concerns.

Prof. David J. Brenner of Columbia University, a radiology researcher who has warned of the cancer risk posed by the X-ray machines, welcomed their removal from large airports, whatever the rationale.

"We do not know the long term public health consequences of exposing many millions of passenger to very low doses of x rays," Brenner said Sunday in an e-mail. "So from a public health perspective this change in policy, which also brings us more in line with the policy in Europe, is most welcome."

The X-ray scanners, which are made by Rapiscan Systems of Torrance, Calif. and cost about $160,000 each, have also raised ethical concerns, after Rapiscan hired former Homeland Security Secretary Michael Chertoff, a former U.S. Attorney for New Jersey, to lobby for their use. Millimeter wave scanners, by L3 Communications of New York, cost about the same. Farbstein said the X-ray/millimeter wave swap did not have a significant cost associated with it.

Scanners went into widespread use in 2010, after an attempt by Umar Farouk Abdulmutallab, nicknamed the Underwear Bomber, to blow up a flight from Amsterdam to Detroit.

Both types of scanners have raised concerns by privacy advocates that they are overly intrusive, prompting the TSA to modify the images they produce.